vim-patch:9.1.0654: completion does not respect completeslash with fuzzy

Problem:  completion does not respect completeslash with fuzzy
          (egesip)
Solution: Change path separator on Windows, depending on 'completeslash'
          option value (glepnir)

fixes: vim/vim#15392
closes: vim/vim#15418

https://github.com/vim/vim/commit/b9de1a057f9a0b6de6f64a9c1b2078c7069cdd7d

Co-authored-by: glepnir <glephunter@gmail.com>

2 files changed, 55 insertions, 1 deletions

diff --git a/src/nvim/insexpand.c b/src/nvim/insexpand.c
index 15ece1cab8..af26e882dc 100644
--- a/src/nvim/insexpand.c
+++ b/src/nvim/insexpand.c
@@ -3318,8 +3318,30 @@ static void get_next_filename_completion(void)
   size_t leader_len = ins_compl_leader_len();
   bool in_fuzzy = ((get_cot_flags() & kOptCotFlagFuzzy) != 0 && leader_len > 0);
 
+#ifdef BACKSLASH_IN_FILENAME
+  char pathsep = (curbuf->b_p_csl[0] == 's')
+                 ? '/' : (curbuf->b_p_csl[0] == 'b') ? '\\' : PATHSEP;
+#else
+  char pathsep = PATHSEP;
+#endif
+
   if (in_fuzzy) {
-    char *last_sep = strrchr(leader, PATHSEP);
+#ifdef BACKSLASH_IN_FILENAME
+    if (curbuf->b_p_csl[0] == 's') {
+      for (size_t i = 0; i < leader_len; i++) {
+        if (leader[i] == '\\') {
+          leader[i] = '/';
+        }
+      }
+    } else if (curbuf->b_p_csl[0] == 'b') {
+      for (size_t i = 0; i < leader_len; i++) {
+        if (leader[i] == '/') {
+          leader[i] = '\\';
+        }
+      }
+    }
+#endif
+    char *last_sep = strrchr(leader, pathsep);
     if (last_sep == NULL) {
       // No path separator or separator is the last character,
       // fuzzy match the whole leader
diff --git a/test/old/testdir/test_ins_complete.vim b/test/old/testdir/test_ins_complete.vim
index 0b1a1bed47..3accb1f286 100644
--- a/test/old/testdir/test_ins_complete.vim
+++ b/test/old/testdir/test_ins_complete.vim
@@ -2966,6 +2966,38 @@ func Test_complete_fuzzy_match()
   unlet g:abbr
 endfunc
 
+func Test_complete_fuzzy_with_completeslash()
+  CheckMSWindows
+
+  call writefile([''], 'fobar', 'D')
+  let orig_shellslash = &shellslash
+  set cpt&
+  new
+  set completeopt+=fuzzy
+  set noshellslash
+
+  " Test with completeslash unset
+  set completeslash=
+  call setline(1, ['.\fob'])
+  call feedkeys("A\<C-X>\<C-F>\<Esc>0", 'tx!')
+  call assert_equal('.\fobar', getline('.'))
+
+  " Test with completeslash=backslash
+  set completeslash=backslash
+  call feedkeys("S.\\fob\<C-X>\<C-F>\<Esc>0", 'tx!')
+  call assert_equal('.\fobar', getline('.'))
+
+  " Test with completeslash=slash
+  set completeslash=slash
+  call feedkeys("S.\\fob\<C-X>\<C-F>\<Esc>0", 'tx!')
+  call assert_equal('./fobar', getline('.'))
+
+  " Reset and clean up
+  let &shellslash = orig_shellslash
+  set completeslash=
+  %bw!
+endfunc
+
 " Check that tie breaking is stable for completeopt+=fuzzy (which should
 " behave the same on different platforms).
 func Test_complete_fuzzy_match_tie()